The correct options are
A 3∫−3x2sinx1+x6.f(x)dx=0
B f(x) is a constant function
C f′(x) is a constant function
Observe that the elements of row R3 are the derivatives of the elements of row R2 and they, in turn, are proportional to the derivatives of the elements of row R1.
Therefore,
f′(x)=∣∣
∣
∣∣R′1R2R3∣∣
∣
∣∣+∣∣
∣
∣∣R1R′2R3∣∣
∣
∣∣+∣∣
∣
∣∣R1R2R′3∣∣
∣
∣∣=0,∀ x∈R
⇒f(x)=constant
As f(0)=∣∣
∣∣61016−22−1123∣∣
∣∣=2
∴f(x)=2, ∀ x∈R
3∫−3x2sinx1+x6.f(x)dx=23∫−3x2sinx1+x6dx
Let g(x)=x2sinx1+x6
g(−x)=−x2sinx1+x6=−g(x)
Hence, g is an odd function.
∴3∫−3x2sinx1+x6.f(x)dx=0